Astigmatic Vector Analysis of Posterior Cornea - a Comparison Among Healthy, Forme Fruste and Overt Keratoconus Corneas

Completed

• Conditions: Keratoconus
• Interventions: Other: Analysis of anterior and posterior corneal surfaces

• Registration Number: NCT02698709
• Lead Sponsor: University of Sao Paulo

Brief Summary

The main purpose of this study is to determine new diagnostic criteria for an eye disease called keratoconus.

Detailed Description

Eyes of patients who distinctly present signs of keratoconus, for both eyes, at corneal tomography (an exam commonly used in such cases), and those who present such signs in only one eye were compared to eyes of unaffected patients. Several characteristics of anterior and posterior corneal astigmatism (special emphasis was given to the latter) were collectively assessed among all patients by a method referred to as vectorial analysis. Statistical tests were then performed, in an attempt to highlight differences among those three groups of patients and, eventually, define new diagnostic criteria.

Basic Information
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Recruitment & Eligibility
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Study & Design
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Trial Locations

Study Timeline

• Study Start: 2015-05
• Primary Completion: 2015-08
• Study Completion: 2015-09
• Status Verified: 2016-02
• Study First Submitted: 2016-02-24
• Study First Submitted QC: 2016-02-29
• Last Update Submitted: 2016-02-29
• Study First Posted: 2016-03-04
• Last Update Posted: 2016-03-04

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 698

Inclusion Criteria

• Good-quality Scheimpflug scans (approved by the device in the ''Examination Quality Specification'').

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Exclusion Criteria

• Previous eye surgery or trauma, and any sort of corneal scarring that might interfere with keratometric data acquisition.

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Study & Design

• Study Type: OBSERVATIONAL
• Study Design: Not specified

Arm && Interventions

Group	Intervention	Description
Forme fruste keratoconus (FFKc)	Analysis of anterior and posterior corneal surfaces	Whether only one eye manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers, and the fellow eye seemed unaffected. Such unaffected eyes were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos.
Healthy corneas (C)	Analysis of anterior and posterior corneal surfaces	Corneas of normal candidates to refractive surgery who did not develop any sign of corneal ectasia after laser in situ keratomileusis during a two year follow-up period were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos.
Overt keratoconus (Kc)	Analysis of anterior and posterior corneal surfaces	Whether both eyes manifested classic Kc-suggestive topographic features, such as corneal steepness higher than 47.20 diopters (D), superior-inferior asymmetry higher than 1.40 D and thinnest pachymetric reading lower than 500 micrometers. Such eyes were analyzed by an Scheimpflug-based tomographer. Vector astigmatism analysis of anterior and posterior corneal surfaces were studied in accordance to method proposed by Thibos.

Primary Outcome Measures

Name	Time	Method
Astigmatism corneal vectors (based on keratometric readings at the three millimeter optical zones for both corneal surfaces).	Through study completion, an average of 6 months.	Corneal tomography at an Scheimpflug-based tomographer

Trial Locations

Locations (1)

Clínica Oftalmológica do Hospital de Clínicas - FMUSP; 🇧🇷 São Paulo, Brazil